1. Field of the Invention
The subject invention is directed to a hemostasis valve for vascular introducers that provides a complete hemostatic seal regardless of the diameter of the object introduced through the valve, while exhibiting lower insertion and extraction forces than prior-art hemostasis valves.
2. Description of Related Art
The percutaneous introduction of diagnostic and therapeutic devices such as pacemaker leads and cardiovascular catheters into a blood vessel is typically accomplished with the aid of an introducer assembly. Introducer assemblies generally include a dilator having a tapered end portion and a thin-walled introducer sheath having a lumen extending through the sheath to initially accommodate the dilator, and subsequently accommodate the passage of a pacemaker lead or catheter.
Typically, the percutaneous introduction of an introducer assembly is accomplished by first inserting a needle into the blood vessel at a desired location and verifying its position by observing fluid return or by a similar method. While the needle is held firmly in place, a guidewire is inserted through the needle cannula to the desired depth. The guidewire is then held in place and the needle is withdrawn. Pressure is applied on the puncture site to minimize blood loss. Next, the introducer assembly is threaded over the guidewire. The introducer assembly is grasped close to the skin surface and advanced through the tissue to the desired position. Then, the dilator and guidewire are removed, leaving the sheath installed. A lead, catheter, or similar diagnostic or therapeutic device is then introduced into the sheath and advanced to the desired position. Lastly, the sheath is removed, leaving the device disposed within the blood vessel.
It is known to configure an introducer sheath so that it may be easily removed or separated from the lead or catheter after it has been put in place. For example, it is known to provide score lines in the wall of the sheath to enable the sheath to be peeled away, slit, or split open. Once the sheath has been removed and the catheter has been put in place, therapeutic medical devices such as endocardial pacing/defibrillation leads may be introduced into the blood vessel through the catheter.
Once the sheath has been inserted into a blood vessel, it provides a passage for the free flow of blood, which may result in significant blood loss from a patient. The sheath also provides an open passage for the introduction of air into the blood vessel, which may cause an embolism in the vascular system of the patient. To overcome these problems, vascular introducers have been developed with hemostatic valves that prevent the free flow of blood through the introducer sheath.
In such prior art devices, the hemostatic valve is configured to create frictional resistance to the passage of therapeutic devices such as flexible cardiac leads. This makes introduction of a lead difficult and can actually cause damage to the lead.
The prior art hemostasis valve designs are not capable of providing an effective hemostatic seal on introduced medical devices having a very wide range of French sizes, and are especially challenged when presented with larger French size devices (e.g. larger than 12F), because such designs use radially aligned slits that form triangular gaps at the slit intersections, which leak blood and/or fluid upon insertion of a medical device. Additionally, such prior art hemostasis valve designs are not capable of sealing a wide variety of French sizes, while still maintaining the ability to break and peel away after use.
There has also been a dramatic increase in the number and types of new medical devices that have large French sizes (e.g. larger than 12F) followed by smaller French sizes (e.g. smaller than 12F) on the same unit. Such combinatorial medical device units pose a challenge that exceeds the capabilities of prior art hemostasis valve designs. Additionally, such prior art hemostasis valve designs are not able to provide effective hemostatic seals when more than one medical device is introduced through the hemostasis valve simultaneously.
There is an urgent need for a hemostasis valve for a vascular introducer that effectively prevents the backflow of blood and other fluids, while accommodating: insertion of medical devices with a wide range of French sizes, insertion of medical devices with combinatorial units of differing French sizes, and/or insertion of multiple medical devices at the same time.